The invention relates to a bearing unit for assemblies or chassis parts of vehicles, in particular to a bearing unit comprising elastomer springs.
Bearing units which comprise elastomeric springs are used as auxiliary frame bearings to receive add-on components or add-on assemblies or chassis parts on the supporting units of a vehicle. Various bearing rigidities are required from the bearing units in order to take account of different extents of freedom of movement and different dynamic properties.
DE 25 49 936 C2 discloses an impact absorber with an elastomeric spring arranged in a rigid casing. The end side of this rigid casing forms one abutment for the elastomeric spring, while the second abutment for the elastomeric spring is formed by a piston capable of movement relative to the rigid casing. The elastomeric spring has a through-opening which runs in the axial direction, and has a cavity formed exclusively by the inside wall of the elastomeric spring and extending over the entire axial length of the elastomeric spring. The design of the elastomeric spring is such that, in every operating condition of the impact absorber, the spring abuts with the entire outer surface on the inner surface of the rigid casing.
DE 2 223 314 relates to a bumper with an elastomeric spring and friction damping. A rigid casing of substantially tubular shape is designed with a widening, the diameter of which is greater than that of the front part of the casing, and which has end faces closed off by virtue of its design. In the front part of the casing there is a piston which can move in the axial direction, the cylindrical elastomeric spring being arranged in the casing axially between the piston and one closed-off end face and having, in the region of the front part of the casing, a substantially uniform external diameter. In order to achieve a radial constraint on the elastomeric spring, this is of a dimension equal to or greater than the internal diameter of the front part of the casing, and the internal diameter of the widening of the casing is dimensioned to allow a limited extent of deformation and kinking of the elastomeric spring.
DE 43 19 689 A1 relates to a support bearing for motor vehicles. The solution proposes a support bearing for vehicles with a progressive spring characteristic. A central supporting rod extends through a receiving opening in a supporting part, for example in the bodywork of a motor vehicle, with radial play. The receiving opening has, surrounding this opening at a distance and securely mounted with respect thereto, cup-shaped receptacles for elastic support elements whichxe2x80x94in relation to the plane of the receiving openingxe2x80x94are open toward opposite sides. In an assembled support bearing, the elastic support elements are held and prestressed with respect to one another between the abutments of the support rod, and hold the support rod so that it is axially and angularly movable with respect to the supporting part. In the assembled condition, there is free space radially between the elastic support elements and the walls of the cup-shaped receptacles, and the elastic support elements are firmly set radially with respect to the cup-shaped receptacles, at least substantially with maintenance of the radial free space between these and the cup walls.
In other prior art solutions, elastomeric components for the various directions are connected to one another. Furthermore, in order to achieve varying rigidities, use is made of inserts made from foreign materials which have an adverse effect on the recyclability of bearing units of this type, since an additional operation is required to bring about separation of the materials.
It is an object of the present invention, in the light of the prior art solutions outlined, to provide a bearing unit whose rigidities can be adjusted independently of one another, and which is easy to assemble and to recycle.
We have found that this object is achieved in that a bearing unit for receiving add-on parts and vehicle components on supporting parts of vehicles comprises at least one elastically deformable component which is supported by a support, and the elastomeric spring components received on this support have no connection to one another.
The advantages achievable with this solution are especially seen in that the separation from one another of each of the elastomeric spring components carried and held on the support means that the rigidities of the bearing unit in a vertical direction, and also in a radial direction, can be adjusted entirely freely and independently of one another. This means that the rigidities in all three coordinate directions can be adjusted independently of one another; and this means that the use of inserts of another material in the bearing unit can be dispensed with, since the rigidities can be adjusted in the desired manner by using appropriate elastomeric spring components, for example components with different hardness, on the support. Thus, simply by inserting elastomeric spring components of different hardness around a 360xc2x0 circle, it is possible to establish different damping characteristics in a radial direction at particular points around the circumference of any particular bearing unit.
In another embodiment of the solution of the invention, the elastomeric spring components have different rigidities which can be brought about, for example, by using different hardnesses for the elements to be inserted or applied. It is, of course, also possible for different hardnesses or rigidities to be achieved through the use of different materials to form the elastomeric spring components.
If the support and the elastomeric spring components are composed of the same base material, such as cellular PU with TPU, the bearing unit of the invention has excellent recyclability, since there is no need to separate different materials within the bearing unit, and the steps required for this purpose in any recycling process can be dispensed with. Alongside excellent recyclability, furthermore, using the same material for support and elastomeric spring components gives good adhesion between the components.
If the support is manufactured from a material other than that used for the elastomeric spring components, for example from a metal core, the elastomeric spring components made from elastomeric material may simply be inserted onto this. Besides inserting the appropriate elastomeric spring components onto the support or into the support, elastomeric spring components may also be bolted, screwed or adhesively bonded to the support.
Another embodiment of the connection of elastomeric spring components to the support unit consists in foaming the elastomeric spring components onto the support unit. If these components are composed of the same base material, the foaming-on requires no adhesion promoter between these components.
To simplify the assembly of a bearing unit according to the invention, the support may be designed with abutment surfaces for the respective elastomeric spring components. Besides this, the support may also be provided with centering devices in the form of centering collars with which, during assembly, the elastomeric spring components to be received onto the support can be placed directly into the correct position, so that no further adjustment procedures are necessary.
For example, in one embodiment radially acting elastomeric spring components can be held by a collar of the support while they are inserted into the interior of the support, and are supported on the surface of its internal circumference, so that the radially acting elastomeric spring components have been received within the support in a manner which allows them to move relative to the same. To allow deformation of the radially acting elastomeric spring components, space is provided between the radially acting elastomeric spring components, and this space serves to receive the deformed material of the respective elastomeric spring component subjected to deformation.
In a preferred method, the support of the bearing unit is received on a frame structure in the region of a supporting part of a vehicle.
The cross section of the opening in the bearing unit proposed according to the invention can be adjusted via the shaping of the radially acting elastomeric spring components. If the radially acting elastomeric spring components have raised regions with a rounded profile, these project into the interior of the bearing unit aperture and, in non-deformed condition, establish a cross section of the opening. Any component which may be introduced into the bearing unit aperture is therefore held and carried by four raised regions of the radially acting elastomeric spring components, these raised regions delimiting the cross section of the opening in the bearing unit.